package day_2022_4_to_7.day48;

import java.util.Scanner;

/**
 * @author haomin
 * @date 2022/05/14 14:08
 **/
public class Day18_1_fib {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int num = in.nextInt();
        System.out.println(fib(num));
    }
    private static int fib(int num){
        if(num == 1 || num == 2){
            return 1;
        }
        return fib(num-1) + fib(num-2);
    }
}